Multiple-voltage power supply circuitry for motor vehicles

ABSTRACT

This invention relates to an electrical power supply circuit for an automobile vehicle.  
     This circuit comprises a primary stage ( 10 ) powered by a main energy source (A 0 , S 0 ). This primary stage outputs an AC current to a current loop (BC) supplying power to at least one primary winding of a transformer. A converter converting AC current to direct current or voltage is associated with the secondary winding of the transformer to create an auxiliary direct current or voltage source.

FIELD OF THE INVENTION

[0001] The present invention generally relates to electrical power supply circuits, configured particularly for use on automobile vehicles.

[0002] More precisely, the present invention relates to an electrical power supply circuit of this type including a main direct voltage source powered by a rotating machine, and at least first and second auxiliary direct voltage sources powered from the main source.

BACKGROUND INFORMATION

[0003] The most conventional and the most widespread electrical circuit architecture at the moment is composed of an alternator driven by the engine of the vehicle and powering a distribution network at a single voltage, for example 14 volts, a 12 volt battery being installed on this network as a buffer.

[0004] Devices consuming electrical energy take power from this network through distribution boxes equipped with fuses that protect the electrical harness by isolating any electricity consumer device from the network if the device becomes defective, and particularly any device in which there is a short circuit.

[0005] In this type of architecture, devices consuming electrical energy can only dialog with each other through a multiplexed information network independent of the electrical energy distribution network.

[0006] The new situation created by the very fast growth in the number of electrical devices on automobile vehicles has recently made some automobile manufacturers consider increasing the voltage output by the electrical energy distribution circuit, for example increasing it to 42 volts instead of 14 volts.

[0007] However, since the construction of some electrical devices makes them inherently unsuitable for such an increase in the power supply voltage, and since a specific adaptation of these devices would lead to prohibitive costs, the planned evolution would initially require the use of at least two distribution networks, outputting electrical energy at two different voltages.

[0008] An example of the architecture of such an electrical energy supply circuit conform with this evolution is illustrated in FIG. 1.

[0009] This type of circuit typically includes a rotating machine, such as an alternator A₀, for example, outputting a voltage of 24 volts, this alternator AO being connected to a rectifier forming a main direct voltage source S₀, for example, outputting a direct voltage V₀ equal to 42 volts.

[0010] A first auxiliary source S_(z) outputting a direct voltage V_(y) equal to 42 volts, is directly formed by the main source S0 buffered by a battery BAT_(y), for example, a 36 volt battery, this first auxiliary source supplying a first distribution network RD_(y).

[0011] A second auxiliary source S_(z) outputting a direct voltage V_(z) equal to 14 volts includes a direct/direct converter powered by the main source S₀, the output of which is buffered by a battery BAT_(z), for example, a 12 volt battery, this second auxiliary source powering a second distribution network RD_(z).

[0012] Conventional solutions may be sufficient to satisfy some needs, and although these solutions use a single voltage as is the case for the classical solution, or at least two voltages as is the case of the architecture illustrated in FIG. 1, but a number of problems can arise with these solutions.

[0013] Firstly, the distribution of electrical energy using a voltage regulated circuit makes it necessary for each consumer device to includes its own direct-direct converter or be dimensioned to accept the available power supply voltage.

[0014] For example, since computers use electronic components that only accept low power supply voltages, usually 3 volts or 5 volts, all computers must be provided with direct-direct converters.

[0015] However, on the other hand, filament lamps must be sized to be supplied at 12 volts since they are too numerous and their value is too low to be fitted with such a converter. However, this size imposes the choice of relatively thin filaments, and consequently their life is not optimized.

[0016] Moreover, since these conventional solutions are designed such that a strong variation in the consumption of electrical energy will change the available voltage on the distribution network, the devices consuming electricity energy must themselves be designed to be able to resist these variations and therefore satisfy a severe specification that increases their manufacturing cost.

[0017] Furthermore, since conventional architectures are designed such that a short circuit in any one of the devices consuming electrical energy could cause an over current in the electrical harness and could destroy it if an appropriate protection is not provided, it is essential that the distribution network should be protected by fuses.

[0018] Finally, since they impose the use of capacitive input stages that naturally act as filters for high frequency signals, these architectures cannot be used as physical supports for carrier current information transmission systems.

[0019] It is an object of the present invention to provide an electrical energy supply circuit for an automobile vehicle, capable of solving at least one of the problems mentioned above due to its inherent principle.

SUMMARY

[0020] Consequently, the circuit according to the present invention includes a primary stage and at least first and second secondary modules forming the first and second auxiliary sources respectively, the primary stage including a primary alternating current generator supplied by the main source, a current loop that carries an alternating current produced by the primary generator, and at least first and second windings installed in series in the current loop and forming primary windings of the corresponding first and second transformers, and each secondary module including a corresponding transformer secondary winding and a current-voltage converter connected to this secondary winding, this current-voltage converter being configured to produce a direct output voltage from the alternating current circulating in the secondary winding.

[0021] Each secondary module may thus be sized such that its output voltage is adapted to the type of device powered by this module.

[0022] Therefore, devices consuming electrical energy are no longer sized under the constraint of an imposed power supply voltage, but they may be sized simply to satisfy the need to optimize its cost with regard to its function.

[0023] Moreover, to the extent that the network is configured for an alternating current, it does not filter high frequency signals, and therefore it may be used as a physical support for a carrier current information transmission system.

[0024] In an example embodiment of the present invention, the primary alternating current generator includes a primary alternating current regulator capable of controlling the amplitude of the current circulating in the current loop, and each secondary module includes a voltage regulator.

[0025] Due to the independence thus introduced between the global load on the circuit and the individual load of the different secondary modules, variations in the load on one such module do not affect the other modules, for which the output voltage is thus protected from any variation.

[0026] Moreover, to the extent that the current in the current loop, in other words in the harness that passes through the vehicle, is regulated in a primary stage, the risk that a short circuit in an electricity energy consumer device may cause a short circuit that would burn the harness is very much reduced.

[0027] For example, the primary alternating current generator may include a resonant circuit installed in series in the current loop and in which oscillations are maintained by pumping electrical charges taken at a given frequency on a charge storage circuit connected to the main direct voltage source and itself including one or several capacitors.

[0028] Consequently, the primary alternating current generator may include a transistor bridge and a driver circuit, the transistor bridge being connected to the charge storage circuit and to the resonant circuit to transfer electrical charges picked up from the charge storage circuit to the resonant circuit, and each pair of transistors in the transistor bridge adopting a cyclically variable conducting state, controlled by an output signal at the determined frequency of the driver circuit.

[0029] The driver circuit itself may include a voltage frequency converter controlled by a control voltage that depends on the direct voltage of the main source, to produce an output signal at the determined frequency, the current regulator including a specific retroaction loop capable of modifying the control voltage of the voltage-frequency converter as a function of the current circulating in the current loop.

[0030] Under these conditions, the voltage regulator provided in each secondary module may be configured to regulate the amplitude of the direct output voltage from the current-voltage converter.

[0031] For example, this current-voltage converter may include a rectifier bridge connected to the secondary winding of the transformer, and a capacitive circuit connected to the secondary winding through an electrical link through the rectifier bridge, this rectifier bridge charging this capacitive circuit.

[0032] In this case, the voltage regulator may include a threshold detector comparing the charging voltage of the capacitive circuit to a predetermined voltage value, and a switching device controlled by the threshold detector to selectively short circuit the secondary winding, and consequently to interrupt the energy transfer between the secondary winding and the capacitive circuit when the charging voltage of this capacitive circuit reaches the predetermined voltage value.

[0033] The advantages of the electrical energy supply circuit according to the present invention are particularly significant in the case in which the transformation ratios of the first and second transformers are different from each other, and the different secondary modules may thus be used to different sized groups of devices consuming electrical energy at different voltages.

[0034] More generally, the present invention relates to an electrical energy supply circuit for an automobile vehicle wherein this circuit includes a primary stage including a main source that outputs an alternating current to a current loop input into a primary winding of a transformer. The secondary winding of this transformer is associated with an alternating current to direct voltage and/or current converter that then forms an auxiliary direct voltage or current source.

[0035] Thus, the electrical energy supply circuit according to the present invention includes a main electricity generator and at least one secondary direct voltage or current power supply.

[0036] There are many advantages in using a current loop. For example, all that is necessary to install a current loop is to install electrical cables passing through all or some of the vehicle for connection to the devices to be powered.

[0037] There may be several transformers, and therefore several secondary power supply sources may power several devices in parallel. Thus, each device only includes its own power supply adaptor.

[0038] According to one example embodiment, the current loop includes a winding forming the secondary of a transformer, the primary of which is powered by a supplementary source of electrical energy, for example, a supplementary independent energy source type.

[0039] In this case, the supplementary source of electrical energy and/or the main source may include an energy storage element, the current being such that it enables energy exchanges between the main source and the supplementary source.

[0040] In one example embodiment, the automobile vehicle is of the electrical traction type and the main energy source is arranged to draw its energy from the power supply source of the electric traction motor, this motor power supply source directly powering this electric traction motor without passing through the current loop, and the auxiliary direct current or voltage source is designed for the power supply of at least one other device on the vehicle.

[0041] According to one example embodiment, the main energy source powers a second primary stage outputting an alternating current to a second current loop that powers the primary of a second transformer, the secondary of which powers a second control device identical to a first control device powered by the secondary of the transformer in the first current loop, this second device being intended to replace the first if there is a failure in the first device.

[0042] In this case, the first and the second devices may be used to control a vehicle safety device such as a braking device.

[0043] In one example embodiment, the circuit includes at least two current loops configured to supply power to devices with various natures, for example, some in the engine compartment and others in the passenger compartment.

[0044] According to another example embodiment, an AC current to direct voltage or current converter includes more than one direct voltage and/or current outputs, for example, with different values.

[0045] In one example embodiment, the current loop includes several complementary connectors that make the loop continuous when they are joined together, or a transformer winding may be introduced into the primary circuit when they are separated.

[0046] The present invention also relates to a module for a circuit according to the present invention that includes a transformer in which the primary winding may be connected in the current loop.

[0047] The present invention also relates to a module for a circuit according to the present invention including a transformer for which the secondary winding may be connected into the current loop.

[0048] Regardless of the arrangement, the current loop (or loops) may be used to transmit information signals.

[0049] Other characteristics and advantages of the present invention will become clear from the following disclosure that is given for guidance and is in no way restrictive, with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0050]FIG. 1 is a schematic diagram illustrating a conventional architecture of the power supply circuit.

[0051]FIG. 2 is a schematic view of the structure of a circuit according to the present invention.

[0052]FIG. 3 is a schematic view illustrating the primary stage of a circuit according to the present invention.

[0053]FIG. 4 is a schematic view illustrating the secondary module of a circuit according to the present invention.

[0054]FIG. 5 is a schematic view illustrating one example embodiment of the present invention including a supplementary independent power supply source.

[0055]FIG. 6 is a schematic view illustrating another example embodiment of the present invention when used in an electrical vehicle.

[0056]FIG. 7 is a schematic view illustrating another example embodiment of the present invention.

[0057]FIGS. 8 and 8b illustrate an example embodiment in which the number of secondary modules connected to the main power supply circuit may be modified.

DETAILED DESCRIPTION

[0058] As illustrated in FIG. 2, the electrical energy supply circuit of the present invention, which is configured particularly for use in an automobile vehicle, includes a main source S₀ of a direct voltage V₀ powered by a rotating machine, such as an alternator A₀, and several auxiliary voltage sources denoted S₁, S₂, S_(n-1) and S_(n) powered from the main power supply source S₀ and that output direct voltages denoted V₁, V₂, V_(n-1) and V_(n) respectively to power distribution networks RD₁, RD₂, RD_(n-1) and RD_(n) respectively.

[0059] As in the architecture illustrated in FIG. 1, one of the auxiliary sources denoted S_(y) and outputting a direct voltage V_(y) may be formed directly by the main source S₀, buffered by a battery BAT_(y) to power a first distribution network RD_(y).

[0060] The circuit according to the present invention includes a primary stage 1 (FIG. 3) and several secondary modules such as S₁ and S₂ (FIG. 2), each of which forms one of the auxiliary sources.

[0061] More precisely, the primary stage 1 includes a primary current generator 10 (FIGS. 2 and 3) that is powered by the main source S₀ and that outputs an alternating current I₁, a current loop BC (FIGS. 2 and 3) in which the alternating current I₁ produced by the primary generator 10 circulates, and several windings, such as E₁₁ and E₁₂, installed in series in the current loop BC, each winding forming the primary winding of a corresponding transformer such as T₁ and T₂.

[0062] According to a second aspect of the present invention, each secondary module, such as S₁ and S₂, includes a winding, such as E₂₁ and E₂₂, forming the secondary winding of the corresponding transformer T₁, T₂ and a current-voltage converter CCV connected to this secondary winding E₂₁, E₂₂.

[0063] Finally, according to a third aspect of the present invention, the current-voltage converter CCV is able to produce a direct output voltage, such as V₁ and V₂, starting from the alternating current such as I₂₁ or I₂₂ that circulates in the secondary winding, such as E₂₁ and E₂₂.

[0064] As illustrated in FIG. 3, which illustrates an example embodiment of the circuit according to the present invention, the primary alternating current generator 10 includes a current regulator 11 that controls the amplitude of the current I₁ circulating in current loop BC, that will be described below.

[0065] This primary alternating current generator 10 also includes a resonant circuit 12, a transistor bridge 13 and a driver circuit 14, the resonant circuit 12 including, for example, a capacitor C12 and an inductance L12 mounted in series in the current loop BC.

[0066] The transistor bridge 13 includes two pairs of opposite transistors, namely the pair 131, 133 and the pair 132, 134.

[0067] The transistor bridge 13 is connected through nodes common firstly to transistors 131, 132 and secondly to transistors 133, 134, to the terminals of a charge storage circuit, for example, composed of one or several capacitors Q.

[0068] This capacitor Q is permanently charged at voltage V₀ by the main direct voltage source S₀ to which it is connected.

[0069] The transistor bridge 13 is also connected through nodes common firstly to transistors 131, 134 and secondly transistors 132, 133, to the current loop BC and particularly to the series resonant circuit 12.

[0070] The driver circuit 14 produces an output signal S14 with two phases in alternation, φ1 and φ2, at a frequency Fc and applied to transistor pairs 131, 133 and 132, 134 respectively to control the conducting state of these pairs of transistors.

[0071] Provided that the frequency Fc is not too different from the natural resonant frequency of the resonant circuit 12, this circuit is also kept in oscillation by the electrical charges injected to it by the transistor bridge 13 at frequency Fc and with an alternating polarity, by pumping these charges from the charge storage circuit Q, at constant polarity.

[0072] The current I₁ set up in the loop BC is a sinusoidal (or almost sinusoidal) alternating current, for which the frequency may, for example, be chosen to be about 70 kHz.

[0073] The resonant circuit 12 may be simplified by eliminating the capacitor C12 such that it only includes an inductance, such as L12, and the oscillations of the inductance may be maintained by appropriate control of the transistors in bridge 13.

[0074] Although economically more attractive, the technical performances of this variant are not as good as the technical performances in the illustrated solution because it results in significant losses.

[0075] As illustrated in FIG. 3, the driver circuit 14 includes a voltage-frequency converter CVF controlled by a control voltage Vc.

[0076] The voltage Vc, that depends on the direct voltage V₀ of the main source S₀, is also controlled by the current regulator 11, the role of which is to adapt the frequency Fc as a function of the current I₁ circulating in the current loop BC.

[0077] More precisely, the current regulator 11 includes a retroaction loop schematically indicated by an alternating current-direct voltage converter 111 and by an amplifier 112, in which a voltage increasing with the amplitude of the alternating current I₁ circulating in the current loop BC is applied to the counterreaction input of the amplifier 112, from the converter 111.

[0078] With this arrangement, the electric charge pumping frequency Fc is regulated to bring the amplitude of the alternating current I₁ to the required value, that may depend on the electrical energy demand from the entire circuit.

[0079] The current-voltage converter CCV in each secondary module, such as S₁ and S₂ (FIGS. 3 and 4), includes a rectifier bridge PR connected to the secondary winding, such as E₂₁ or E₂₂ of the corresponding transformer, T₁ or T₂, and a capacitive circuit K.

[0080] The capacitive circuit K is connected to the secondary winding of the corresponding transformer through the rectifier bridge PR that charges this capacitive circuit K at constant polarity.

[0081] Each secondary module (FIG. 4) also includes a voltage regulator RGV, the role of which is to regulate the amplitude of the direct output voltage, such as V₁ or V₂, output by the current-voltage converter CCV.

[0082] For example, the voltage regulator RGV includes a switch J controlled by a threshold detector DS.

[0083] The function of the threshold detector DS is to compare the charging voltage of the capacitive circuit K with a set voltage value supplied to it, such as V_(s1), and to control the switch J so as to connect the capacitive circuit K to the secondary winding of the corresponding transformer through bridge PR for an energy flow when the charging voltage of this capacitive circuit K is less than the set value V_(s1), and so as to isolate the capacitive circuit K in the secondary winding from the energy flow by short circuiting the secondary winding when the charging voltage of this capacitive circuit K reaches the set value V_(s1), the bridge PR being non-conducting and thus preventing capacitive circuit K from discharging through the closed switch J.

[0084] The arrangement of functions described above may be used by circuits with various structures.

[0085] In particular, in the case in which the rectifier bridge PR is not formed of diodes, or is not formed solely of diodes, unlike the normal case, but is composed partially of two transistors installed in series between the terminals of the secondary winding of the corresponding transformer on each side of a terminal in the capacitive circuit K and performing a synchronous rectification at the frequency of the primary current, the switch J may include these two transistors, which simultaneously changeover to the conducting state to fulfil the closing function of this switch J.

[0086] According to the present invention, the various secondary modules are used to power various families of devices consuming electrical energy, arranged in groups at least as a function of their technology, their energy needs and possibly their layout in the vehicle.

[0087] For example, a 100 volt module may be provided at the front of the vehicle to power discharge lamps. Another 7 volt module may be provided near the front of the vehicle to power filament lamps and computers under the bonnet. A third 14 volt module may be provided in the vehicle passenger compartment to power medium power devices, such as the Hi-Fi system, etc.

[0088] Considering this diversity, in practice it is useful to make sure that the transformation ratios of the various transformers associated with different secondary modules, in other words the ratios of the number of turns in the primary and secondary windings in these transformers, are different, at least in some cases.

[0089] Thus, if the numbers of turns in the primary and secondary windings in the transformer T₁ associated with module S₁ are N₁₁ and N₂₁ respectively, and if the numbers of turns in the primary and secondary windings of transformer T₂ associated with module S₂ are N₁₂ and N₂₂ respectively, then, for example, values are selected such that the ratios N₁₁/N₂₁ and N₁₂/N₂₂ are different from each other.

[0090] The circuit according to the present invention in which it is possible to use power supply cables as the physical medium for the transmission of information by carrier current, significantly optimizes wiring of the vehicle.

[0091] Furthermore, since it is possible to send information about the global electrical energy demand to the primary stage by carrier current, the circuit according to the present invention makes it possible to optimize its instantaneous efficiency, since the primary current may then be adjusted to be the right value to output exactly the required power at the maximum voltage, with no excess and therefore no unnecessary losses.

[0092] Several other example embodiments of the present invention are described below with reference to FIGS. 5 to 8.

[0093] In the example embodiment illustrated in FIG. 5, a supplementary independent power supply source for direct or alternating current is provided in a current loop 56 according to the present invention.

[0094] A supplementary independent power supply source 52 in a vehicle may be used for various operations, such as providing energy necessary to start the vehicle (when the main vehicle power supply source is inactive), or to supply power to several secondary devices, such as air conditioning.

[0095] For example, this supplementary power supply source 52 may be a fuel cell, a small thermal combustion engine driving an alternator, a device for recuperation of heat energy lost from the main engine (Peltier cell or turbine driven by exhaust gases), a kinetic energy recuperation device during braking phases, or even another alternator.

[0096] In conventional vehicles, the presence of a second energy source requires the presence of supplementary protection by fuses, which increases costs and the complexity of the electrical network.

[0097] The incorporation of one (or several) supplementary source(s) in a circuit 50 according to the present invention does not make it necessary to provide supplementary protection by fuse.

[0098] In the example embodiment illustrated in FIG. 5, the supplementary source 52 is incorporated in the electrical circuit 50 of the vehicle by connecting this supplementary source to a secondary module S_(N) located in the current loop 56.

[0099] Like the other modules S₁, S₂, . . . , S_(N-1) inserted in the loop 56, this module S_(N) includes a transformer with windings 51 and 53. When the source 52 is active, a winding 51 in loop 56 forms a secondary winding that outputs energy to this loop 56.

[0100] If the source 52 outputs a direct voltage or current, an inverter is added to it, for example, located in module S_(N).

[0101] The elements of the electrical circuit 50 such as the primary generator 10 and secondary modules S₁, S₂, . . . , S_(N-1) may be powered either by the main source S₀ or the supplementary source 52.

[0102] In the example embodiment illustrated, the secondary modules are powered by the source A₀ and/or the source 52, but various other power supply combinations are possible, including particularly:

[0103] 1. The primary generator 10 is powered by the main power supply source A₀, such as a rotating machine driven by the thermal combustion engine, whereas several secondary modules form power supplies of the same type as module S_(N) with an independent source.

[0104] 2. The primary generator 10 is powered by an independent source that becomes a main source.

[0105] In this case, it may be possible for a rotating machine driven by the vehicle engine to be connected to a secondary module of the same type as module S_(N). One or several supplementary independent sources may also each be connected to a secondary module of the same type as module S_(N).

[0106] 3. The primary generator 10 is not powered or does not exist. But the loop 56 is powered using at least one independent source, in other words at least one module of the same type as module S_(N).

[0107] In this context, the primary stage may include the secondary module(s) powered by one (or several) independent source(s).

[0108] Different methods may be used to store energy, and particularly:

[0109] In a first example embodiment, energy is stored only at the input to the primary circuit, for example using battery BAT_(y).

[0110] In another example embodiment, several storage facilities are provided, one of the input to the primary circuit and others at the outputs from some secondary modules.

[0111] Furthermore, it is also possible to eliminate the storage at the input to the primary circuit and to keep the storage at the output from some secondary modules, or possibly even to no longer store any energy.

[0112] If energy is no longer stored, the independent source 52 supplies the initial energy to start up a thermal combustion engine. In other words, in this case, there is no need for the battery.

[0113] The supplementary source 52 may also be put into service at the same time as the main source A₀, S₀, if the main source fails or is insufficient, for example, to add to the power supply for use by a device.

[0114] This supplementary independent source 52 may also be brought into service when the main source S₀ is not in operation, for example, when the engine is not running and the alternator A₀ is not supplying any power.

[0115] Furthermore, the source 52, like the alternator A₀, may be used to charge batteries, for example, the battery BAT_(y).

[0116] In one variant, a supplementary battery is associated with source 52. This supplementary battery is then charged by source 52 and/or the main source.

[0117] In this case, energy exchanges may occur between the battery BAT_(y) and the supplementary battery or the source 52 if it is a battery.

[0118] The presence of an independent source simplifies management of energy stored in the battery used to start a thermal combustion engine.

[0119] The presence of at least one auxiliary source controls air conditioning using one or more compressors driven by an electric motor instead of using mechanical compressors driven by the vehicle thermal combustion engine, this independent source thus avoiding the need to discharge the vehicle battery. The independent source may also be chosen to be more efficient than a thermal combustion engine driving an alternator. Furthermore, an independent source may be less polluting than the thermal combustion engine.

[0120] The network 50 illustrated in FIG. 5 provides the same advantages as the other example embodiments, particularly a galvanic isolation between sub-networks connected to each module S₁, S₂, . . . , S_(N-1) and circuit 50.

[0121] Consequently, a short circuit in one of the subnetworks connected to a module S₁, S₂, . . . , S_(N-1) has no effect on the other sub-networks or on the main circuit 50.

[0122] The use of the present invention in a vehicle with electric traction or hybrid traction is described below with reference to FIG. 6. This use is particularly appropriate since safety standards impose galvanic separation between high voltage network(s) powering the vehicle traction motor and low voltage electrical network(s) powering other devices, such as light bulbs or signal bulbs, windshield wipers, etc.

[0123] Thus, the network 60 illustrated in FIG. 6 includes a main source 62 outputting a high voltage (for example, 115 V) to a main generator 10, to a battery BAT_(y) and an electrical motor 68.

[0124] As in other example embodiments, the main generator 10 transforms this high voltage into an alternating current circulating in loop 56.

[0125] This current loop 56 powers the primary windings P₁, P₂, . . . , P_(N-1) of transformers forming part of secondary modules S₁, S₂, . . . , S_(N-1) arranged in loop 56.

[0126] Thus, the galvanic isolation between the primaries P₁, P₂, . . . , P_(N-1) and the secondaries of the transformers in modules S₁, S₂, . . . , S_(N-1), provides the galvanic isolation required by standards between the high voltage circuit and the low voltage circuit(s) connected to the output(s) of the secondary module(s) S₁, S₂ , . . . , S_(N-1).

[0127] Furthermore, a circuit according to the present invention is capable of transmitting high electrical energy to devices consuming large quantities of energy consumption, such as air conditioning, which is necessarily electric on this type of vehicle. For example, for the same cable cross-section in the loop, it is possible to transfer 115/14 times more power than on a vehicle equipped with a 14 V network (or 115/42 times more power than on a vehicle equipped with a 42 V network).

[0128] If this power gain is not necessary, the cost of the electrical installation may be reduced by reducing the cross-section of the cables in the loop.

[0129]FIG. 7 illustrates use of the present invention in the case in which the control of some devices in the vehicle is doubled up for safety reasons.

[0130] It is conventional that some devices vital to operation of the vehicle or safety of the passengers may be protected against a possible power supply failure or a failure of the control devices. For example, this is applicable for electrically controlled brakes or a steering system with no steering column.

[0131] This result is usually achieved by doubling up the power supplies and circuits transmitting control signals. Thus, the vital devices are connected to two actuators to which the same control signals are applied and/or to two identical power supplies.

[0132] A single actuator and/or a single power supply is (are) active at the same time, the redundant actuator and/or power supply only being effective if there is a failure in the first actuator and/or the first power supply.

[0133] In the example embodiment of the present invention illustrated in FIG. 7, two circuits 70 ₁ and 70 ₂ are provided and are connected to the same main source S₀, to make a redundant power supply for vehicle safety devices, each of these circuits including a primary generator 10 ₁ and 10 ₂, a current loop 78 ₁ and 78 ₂ and secondary modules S₁₁, S₂₁, . . . , S_((N-1)) and S₁₂, S₂₂, . . . , S_((N-1) 2).

[0134] The secondary module S₁₁ on circuit 70 ₂ powers a control device 74 ₁ for a vehicle safety device 74 ₂ and module S₁₂ in circuit 70 ₂ powers another control device 74 ₂ for device 72.

[0135] Device 74 ₂ powered by module S₁₂ is identical to the control device 74 ₁ powered by module S₁₁. If the device is a brake, these devices 74 ₁, and 74 ₂ may, for example, be electric motors to apply the brake, each of these motors 74 ₁, 74 ₂ acting on the same brake control shaft 76.

[0136] Thus, if there is a failure in device 74 ₁, the second device 74 ₂ changes from the standby state to the active state and takes over from the device that has failed.

[0137] Failure of an actuator (or control device) may be caused either by the device 74 ₁ itself or by a failure in the generator 10 ₁ or an element of module S₁₁, or by a failure of the loop 78 ₁. A failure may also be due to a loss of control signals from device 74 ₁.

[0138] In general, the present invention provides security against failures, since failure of the secondary module (apart from a break in the primary winding of a transformer) does not affect the other secondary modules connected on the same loop.

[0139] In another example embodiment of the present invention illustrated in FIG. 8, an electrical energy supply circuit includes devices to vary the number of secondary modules laid out in a current loop 80 in an electric circuit according to the present invention.

[0140] In this respect, pairs 90 of supplementary male connectors 82 and female connectors 84 are provided. These pairs 90 are provided on the conductor 80 of the current loop.

[0141] In order to add a secondary module S_(i), the male conductor 82 (FIG. 8a) is separated from the female connector 84 and the female connector 84 i (FIG. 8b) of module S_(i) is attached to the male connector 82 of conductor 80. The female connector 84 of conductor 80 is attached to the male connector 82 _(i) of module S_(i).

[0142] Current may thus circulate in the current loop 80 and in the winding 88 of the new secondary module S_(i).

[0143] In one example embodiment, the vehicle includes at least two current loops. The number of current loops may depend on the layout of the different devices in the vehicle. For example, one loop powers devices under the vehicle bonnet, in other words in the engine compartment, and another loop powers devices located in the passenger compartment.

[0144] The choice of the number of loops may also be made as a function of communication protocols using carrier currents. For example, one loop powers devices dialoguing according to the VAN protocol and another loop is provided to power devices dialoguing according to the CAN protocol.

[0145] According to another example embodiment, at least one secondary module is capable of producing several direct voltages, with the corresponding transformer including several secondary windings with different numbers of turns. Under these conditions, the number of secondary modules may be limited since the same module may power different types of devices at different voltages.

[0146] Some devices may be powered directly with alternating current, and there may be no need for every secondary module to include a direct voltage or current source. In particular, filament lamps or some resistances, particularly heating resistances, may be powered with alternating current.

[0147] In one variant of the circuit described with relation to FIG. 4, the switch J configured to cut off the direct power supply or the direct current load is connected to the terminals of a primary winding E₁₁, rather than to the terminals of a secondary winding E₂₁ as illustrated in FIG. 4. 

1. Electrical power supply circuit for an automobile vehicle, characterised in that it comprises a primary stage (10) powered by a main energy source, this primary stage outputting an alternating current to a current loop (BC; 50; 60; 70; 80) supplying power to at least one primary winding of a transformer, a converter converting alternating current to direct current or voltage being associated with a secondary winding of the transformer to create an auxiliary direct current or voltage source.
 2. Circuit set forth in claim 1, in which the main energy source comprises a rotating machine such as an alternator (A₀).
 3. Circuit set forth in claim 2, in which the rotating machine powers a direct source (S₀, BAT_(y)) on the input side of the primary circuit.
 4. Circuit as claimed in any one of the previous claims, in which the current loop is used to transmit information signals.
 5. Circuit as claimed in any of the previous claims, in which the current loop comprises a winding forming the secondary (51) of a transformer, the primary (53) of the transformer being powered by a supplementary electrical energy source (52).
 6. Circuit set forth in claim 5, in which the supplementary electrical energy source and/or the main source comprises an energy storage element, and in that the current is such that it enables energy exchanges between the main source and the supplementary source.
 7. Circuit as claimed in any one of the previous claims, in which the automobile vehicle is of the type with electric traction, the main energy source (62) being arranged to draw its energy from the power supply source for the electric traction motor (68), this engine power supply source supplying energy directly to this electric traction motor without passing through the current loop, the auxiliary direct current or voltage source (S₁, . . . , S_(N-1)) being intended for the power supply of at least one other device on the vehicle.
 8. Circuit as claimed in any one of the previous claims, in which the main energy source (A₀, S₀) powers a second primary stage (10 ₂) outputting an alternating current to a second current loop (78 ₂) that powers the primary of a second transformer, in which the secondary of this transformer powers a second control device (74 ₂) identical to a first control device (74 ₁) powered by the secondary of the transformer of the first current loop (78 ₁), this second device being intended to replace the first if there is a failure in the first device.
 9. Circuit set forth in claim 8, in which the first and second devices are intended to control a safety device (72) on the vehicle such as a braking device.
 10. Circuit as claimed in any one of the previous claims, characterised in that it comprises at least two current loops intended to supply power to different types of devices, for example some in the engine compartment and others in the passenger compartment.
 11. Circuit as claimed in any one of the previous claims, in which the converter converting alternating current to direct voltage or current comprises several direct voltage and/or current outputs preferably each with different values.
 12. Circuit as claimed in any one of the previous claims, in which the current loop comprises several complementary connectors (90) that can be used together to maintain continuity of the loop (80) or can be separated so that a winding of a transformer can be inserted in the primary circuit.
 13. Circuit as claimed in any one of the previous claims, in which the secondary winding of the transformer directly supplies alternating current to a device in the vehicle such as a filament lamp or an electric resistance.
 14. Circuit as claimed in any one of the previous claims, in which the primary alternating current generator (10) comprises a current regulator (11) capable of controlling the amplitude of the current (I₁) circulating in the current loop (BC).
 15. Circuit as claimed in any one of the previous claims, in which the primary alternating current stage (10) comprises a resonant circuit (12) installed in series in the current loop (BC) and kept in oscillation by pumping electrical charges taken at a determined frequency (Fc) from a charge storage circuit (Q) connected to the main direct voltage source (S₀).
 16. Circuit set forth in claim 15, in which the main primary alternating current stage (10) comprises a transistor bridge (13) and a driver circuit (14), the transistor bridge (13) being connected to the charge storage circuit (Q) and to the resonant circuit (12) to transfer electric charges taken from the charge storage circuit (Q) to the resonant circuit (12), and each pair of transistors (131, 133; 132, 134) in the transistor bridge (13) being in a cyclically variable conducting state controlled by an output signal (S₁₄) from the driver circuit (14) with a determined frequency (Fc).
 17. Circuit set forth in claim 16, in which the driver circuit (14) comprises a voltage-frequency converter (CVF) controlled by a control voltage (Vc) that depends on the direct voltage (V₀) of the main source (S₀) to produce the output signal (S₁₄) at the determined frequency (Fc), and in that the current regulator (11) comprises a retroaction loop (111, 112) designed to modify the control voltage (Vc) of the voltage-frequency converter (CVF) as a function of the current (I₁) circulating in the current loop (BC).
 18. Circuit as claimed in any one of the previous claims, in which at least one secondary module (S₁, S₂) comprises a voltage regulator (RGV) capable of regulating the amplitude of the direct output voltage (V₁, V₂) from the current-voltage converter (CCV).
 19. Circuit set forth in claim 18, in which the current-voltage converter (CCV) comprises a rectifier bridge (PR) connected to the secondary winding (E₂₁, E₂₂) of the transformer (T₁, T₂) and a capacitive circuit (K) connected to the secondary winding (E₂₁, E₂₂) through an electric link through the rectifier bridge (PR), this rectifier bridge (PR) charging this capacitive circuit (K).
 20. Circuit set forth in claim 19, in which the voltage regulator (RGV) comprises a threshold detector (DS) comparing the charging voltage of the capacitive circuit (K) with a predetermined voltage value (V_(S1), V_(S2)) and a switching means (J) controlled by the threshold detector (DS) to selectively short-circuit the secondary winding (E₂₁, E₂₂) when the charging voltage of the capacitive circuit (K) reaches the predetermined voltage value (V_(S1), V_(S2)).
 21. Circuit as claimed in any one of the previous claims, in which the secondary loop comprises first and second transformers (T₁, T₂) with transformation ratios (N₁₁/N₂₁; N₁₂/N₂₂) that are different from each other.
 22. Circuit set forth in claim 15, in which the charge storage circuit (Q) comprises at least one capacitor. 